topic How to print the "negative float point number" to show negative value? in i.MX RT Crossover MCUs

How to print the "negative float point number" to show negative value?

felix1 — Fri, 17 Jul 2020 10:01:52 GMT

If I use

PRINTF("negative float test = %f", -1.234);

to print the negative float point number, I got the positive value from console, like

"negative float test = 1.234000"

Can you help me to fix it to show the real negative value?

p.s. define PRINTF_FLOAT_ENABLE=1

Re: How to print the "negative float point number" to show negative value?

kbelete — Tue, 21 Jul 2020 15:43:08 GMT

Hi Felix,

Negative floating point values can be printed by opening the Project Properties and defining both “PRINTF_FLOAT_ENABLE” and “PRINTF_ADVANCED_ENABLE” to 1 in the Preprocessor settings. This is shown below using the hello_world SDK example project.

Let me know if this solution works for you. If not, could you provide more details on your environment to help find a solution?

Regards,

Kaleb Belete

Re: How to print the "negative float point number" to show negative value?

felix1 — Wed, 22 Jul 2020 12:06:34 GMT

Hi Kaleb,

Thanks for your right answer.

I want to ask another question about floating point number.

I use CMSIS DSP library to do FFT (fast Fourier transform), this transform will use real number and complex number.

I use "Redlib (nohost-nf)" library now, and it seems ok to compile FFT API like "arm_rfft_fast_f32()".

Do I need to change the "Redlib (nohost-nf)" to another library for using floating point number?